Tube finning machine and method of use

ABSTRACT

This invention relates to a tube finning machine ( 10 ), and in particular to a machine capable of fitting several fins ( 26 ) to one or more tubes ( 26 ) at the same time, the assembled finned tube being suitable for heat exchange applications. According to one aspect of the invention there is provided a tube finning machine for mounting extended surface members ( 96 ) upon one or more tubes, the machine having a base ( 10 ), carrier means movable relative to the base, drive means ( 20 ) for moving the carrier means ( 18 ) in a longitudinal direction, and cartridge means ( 24 ) for locating a plurality of extended surface members ( 26 ), the cartridge means having respective support means ( 30 ) for each extended surface member, and at least some of the support means being movable relative to the cartridge. There is also provided a method of using a machine as herein defined for finning a tube.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 USC 371 to InternationalPatent Application No. PCT/IB01/01859 filed on Oct., 8, 2001, which inturn claims priority to Great Britain Patent Application No. 0024625.6filed on Oct. 7, 2000.

FIELD OF THE INVENTION

This invention relates to a tube finning machine and method of use, andin particular to a machine capable of fitting several extended surfacemembers (or fins) to one or more tubes at the same time, the assembledfinned tube being suitable for heat exchange applications. In oneaspect, the present invention is an improvement to a machine such asthat disclosed in patent application WO96/35093.

BACKGROUND TO THE INVENTION

Often it is necessary to cool a working fluid, and it is known for thispurpose to use a heat exchanger. Heat exchangers often comprise one ormore metallic tubes suspended between two tube plates. The working fluidto be cooled, which may for example be water or oil, flows through thetubes, whilst the coolant passes around and between those tubes, theworking fluid giving up its latent heat to the tubes and thus to thecoolant.

The effective surface area of a tube can be enlarged in order toincrease the heat transfer, as by the addition of one or more annularextended surface members or fins in thermal contact with the outersurface of the tube. Such finned tubes are particularly useful if thecoolant has a low viscosity, and if the coolant is a gas, such as air.

If the tubes are to withstand the internal pressure of the fluid to becooled, the addition of the fins should not reduce or significantlyreduce the tube bursting strength. If the fins are to increase the heattransfer they should not significantly inhibit the flow of coolant, andpreferably should encourage turbulent coolant flow.

The tubes to be used for heat exchangers should meet certain standards(in the UK for instance British Standard 2871 Part 3), these standardsbeing relevant also for those tubes which are formed by extrusion toprovide selected internal formations chosen to enhance internalturbulent flow i.e. to avoid laminar or stratified flow of the workingfluid to be cooled; desirably the tube finning should not reduce thoserespective standards e.g. of tube wall thickness and thus of strength,or of tube uniformity and fin engagement and thus of heat transfer tothe fins.

The fins should be positioned on the tube so as to encourage maximumheat transfer to the coolant, which will not occur if the fin spacing isirregular, or if the fin angles are irregular (with an annular gap ofvarying axial length between adjacent fins).

If the tube walls need to be thinned to accept the fins, one or more ofthe tubes may burst in service and need to be plugged; if the fins areirregularly spaced and/or angled the performance of the heat exchangerwill be reduced.

It is a known design criterion when constructing a matrix or array offinned tubes for a heat exchanger both to arrange the tubes as close toeach other as possible (to reduce the size of the heat exchanger), andto have a maximum area available for thermal transfer between theworking fluid and the coolant (to maximise the possible heat exchange).When utilising tubes fitted with the known annular fins in such anarray, the spacing between the tubes will be limited by the outerdiameter of the fin(s); if as is usual the fins have circular outerperipheries there are areas between adjacent tubes which do notcontribute to heat transfer, and a finning method and machine permittingfins to be fitted which can utilise these areas is desirable.

The performance of a heat exchanger in part depends upon the number offins fitted to a tube, and to the total number of fins i.e. to theaggregate extended area available for heat exchange, as well as to thepositioning and disposition of those fins.

When seeking to overcome the disadvantage of the unused heat-exchangearea caused by the use of fins with a circular periphery, it is known toreplace the separate fins of adjacent tubes by axially-spaced“common-fins” i.e. fins which engage (and interconnect) several tubes.Typically, a common-fin takes the form of an extended plate havingseveral apertures, each aperture being adapted to receive a respectivetube, the plate-like common-fin being in simultaneous thermal contactwith several tubes, and being adapted to transfer the heat from all ofthe tubes across the full area therebetween. An array of tubes to whichare mounted a plurality of multi-apertured common-fins is referred toherein as a “fin block”, though in other documents it is also referredto as a “coil block” or “block fin”.

It will be understood that in a fin block, each fin can be continuousbetween and around each tube in the block, so that a minimum of heattransfer area is wasted. It will be further understood that the tubes ineach block are fixed relative to the other tubes of that block by theprefitted plate-like common-fins.

A known further advantage of such assembled fin block is its relativeease of fitment into a heat exchanger. Thus, for a heat exchangerrequiring two hundred separate finned tubes for instance, each of thetwo hundred tubes must be fitted to both tube plates, and perhaps alsoto separate support plates as may be required for longer tubes. However,if a fin block is prepared having twenty tubes, then only ten suchblocks are required to be handled and fitted.

In a known method of manufacturing a fin block, a stack of common-finsis arranged, adjacent fins being axially spaced by a distance to suitthe requirements of a particular heat exchanger; each common-fin hasseveral apertures, the apertures corresponding in pattern to therequired tube arrangement. The apertures are slightly larger than theoutside diameter of the tubes, and the common-fins are held with theirrespective apertures aligned. The tubes are then individually passedthrough the apertures, and when in position a “bullet” is pulled througheach tube, to expand the tube wall into mechanical contact with therespective fin apertures. A method of this general type is disclosed inU.S. Pat. No. 3,889,745.

This method is not suitable for extruded tubes having internalformations (e.g. for promoting turbulent flow of the liquid to becooled), since a bullet cannot be passed through such tubes.

Another disadvantage of this known bulleting method is that the wallthickness of the tubes is limited by the need for the wall to bestretched by the bulleting operation, so that thinner-walled tubes haveto be used than might otherwise be desired; for example, in practice fora stainless steel tube with an outer diameter of 0.75″ (19.05 mm) it israre for tube thicker that 22 Gauge (“Standard Wire Gauge”) to bebulleted. A further disadvantage is that the bulleting operationintroduces stress into the tubes, and can change the grain structure;the stress is typically not removed by heat treatment since the heattreatment would act also to soften the fins and reduce the thermalcontact between the fins and tubes, i.e. the stress induced by thebulleting operation typically remains in the tube and thus in the heatexchanger as an unwanted side effect of this method of production. Yetanother disadvantage is that the material specification of the tubes canbe altered by the bulleting operation; for example, if the heatexchanger user specified that annealed tubes should be used, thebulleting operation can in some circumstances alter the annealedmaterial into a non-annealed hardened state. Another furtherdisadvantage is that the tube must be of deformable material, solimiting the material which can be used.

Bulleting can also result in non-parallel finning. As the bullet ispulled through the tube, the tube wall can form an angled “front” whichmoves down the tube immediately ahead of the bullet, as a “ripple”;adjacent fins subject to the “ripple” are likely either to be movedalong the tube, or to adopt different angles relative to the tube,resulting on occasion with parts of adjacent fins touching and withother parts spaced by a greater distance than intended. The expansioncaused by the bullet is such that once the bullet has passed a fin, theposition of the fin cannot subsequently be corrected or altered.

Usually when “rippling” is seen to be occurring during tube finning thebullet has nevertheless to be fully drawn through the tube so that itcan be reused, even though the manufacturer recognises that theresulting finned tube is likely to be rejected as unsuitable for heatexchanger use. Also, if a set of tubes is finned whilst in position in aheat exchanger array, any fin displacement which occurs upon internaland thus non-visible tubes cannot be observed, so that the resultingloss of heat exchanger performance might not be realised until theexchanger is in service.

U.S. Pat. No. 3,733,673 discloses a machine for fitting several fins toone or two tubes at the same time. The fins are arranged in a cartridge,and held along their top and bottom edges. Each fin has a number ofapertures therein which are sized and shaped to correspond closely withthe outer periphery of the tubes to be fitted thereinto. The machine ispneumatically actuated and can drive one or two tubes at a time thoughthe aligned apertures in the fins. Following insertion of the fin orfins, the machine can subsequently be used to insert one or two furthertubes into respective apertures of the fins, until all of the tubes havebeen inserted thereinto.

It is a disadvantage of this machine that the cartridge provides onlylimited support for the fins, and so the fins need to be sufficientlyrigid to remain undeformed by the insertion of the tubes. On the otherhand, it is desirable that there be sufficient engagement between thetubes and the fins to ensure good heat transfer therebetween, and it isalso desirable that the fins be as thin as possible to reduce the weightof the assembled fin block and also to maximise heat transfer. Acompromise is therefore necessary between reducing the thickness of thefins so as to maximise heat exchange, and increasing the thickness ofthe fins so as to ensure that the fins do not become deformed as thetubes are forced therethrough. A further compromise is necessary betweenarranging the fins to be a tight fit upon the tubes (so as to maximisethe heat transfer therebetween), and arranging the fins to be a loosefit upon the tubes so that the tubes can be moved more easilytherethrough with a reduced likelihood of deformation of the fins.

It is another disadvantage of this machine that only two tubes can beinserted into the fins at a time, so that considerable time is taken toproduce a large fin block. The provision of a maximum of two tubes isdue to some extent to the maximum power of the machine, but greaterrelevance is understood to be given to the practical disadvantage thatas more tubes are inserted at the same time, the greater is thelikelihood of deforming some of the fins.

A machine for making fin block (though it could also apply individualfins to individual tubes) is disclosed in WO96/35093. That machineutilises a linear motor to drive a fin (or common-fin) onto one or moretubes. In an alternative method of using the machine, a first fin can bedriven onto the end of the tubes, and a second fin driven intoengagement therewith, both fins subsequently being driven along thetubes to their predetermined positions. It is accepted that the collarsof the two fins will interlock in such circumstances, and it isnecessary that the machine have sufficient power to drive suchinterlocked fins.

SUMMARY OF THE INVENTION

The present invention seeks to improve upon the prior art machinesdescribed above, and seeks to reduce or avoid the disadvantagesassociated therewith.

According to a first aspect of the invention there is provided a tubefinning machine for mounting extended surface members or fins upon oneor more tubes, the machine having a base, carrier means movable relativeto the base, drive means for moving the carrier means in a longitudinaldirection, and cartridge means for locating a plurality of extendedsurface members, the cartridge means having respective support means foreach extended surface member, and at least some of the support meansbeing movable relative to the cartridge.

The machine according to the third aspect differs from that of U.S. Pat.No. 3,733,673 in that the fins are able to “nest” together upon thetube. Thus, it is known for the fins to have collars surrounding thetube-receiving apertures, one purpose of the collars being to increasethe area of contact between the tube and the fin. However, in manyapplications it is desired that the fins are sufficiently closely spacedfor the collar of one fin to engage the collar of the adjacent fin. Ifthe fins are pressed together the collars can interlock, serving tofurther secure the fins in position upon the tube. However, when thefins are to be moved relative to the tube(s) during the finningprocedure, it is not desired that the collars interlock since thisincreases the frictional resistance to movement, and so the fins aredeliberately spaced apart by the cartridge. With a machine according tothe first aspect each fin can be moved to a predetermined position uponthe tube(s), whether or not the fins have collars, and whether or notthose collars are desired to interlock.

According to a second aspect of the invention there is provided a tubefinning machine for mounting extended surface members upon one or moretubes, the machine having a base, carrier means movable relative to thebase, drive means for moving the carrier means, and cartridge means forlocating a plurality of extended surface members, the cartridge meanshaving a respective support means for each extended surface member, eachsupport means spanning a substantial part of the extended surfacemember.

The machine according to the second aspect differs from that of U.S.Pat. No. 3,733,673 in that a greater area of the fins are supported bythe cartridge means, reducing the likelihood of the fins becomingdamaged or distorted during tube finning. Alternatively stated, the finsmay be made thinner, and their engagement with the tube(s) increased, soas to enhance the heat transfer, with less risk of distortion.

According to a third aspect of the invention there is provided a tubefinning machine for the manufacture of a heat exchange fin block, whichmachine includes a base, carrier means movable relative to the base,drive means for moving the carrier means, and cartridge means forlocating a number of fins, a clamping means mounted to the base forclamping a portion of at least one tube in a substantially fixedposition relative to the base, the cartridge means being connected tothe carrier means so that the number of fins can be moved to an axiallypredetermined position relative to the tube(s).

The machine according to the third aspect differs from that of U.S. Pat.No. 3,733,673 in that the fins are moved relative to the substantiallystationary tube(s). This has a significant advantage when the machine isused to assemble larger fin blocks. Thus, it will be understood thatwhilst a number of fins can be driven along the tube(s) by the presentmachine (and one or two tubes can be driven through a number of fins bythe prior art machine), the power of the machine determines the maximumnumber of fins which can be used at any one time, i.e. the machine mustbe able to exceed the combined frictional resistance of the fins andtube(s). If a fin block has two tubes and one thousand common-fins, forexample, it is not likely to be practical to build a machine havingsufficient power to fit all of those fins at one time, and instead itwould be practical to fit a smaller number of common-fins (or a “set” ofcommon-fins) at one time, for example twenty common fins, andsuccessively to fit fifty such sets. With a machine in which the tubesmove, there would need to be a means of supporting the previously-fittedfins as they are moved with the tubes, and the means to move the tubeswould need to be robust enough to withstand and move the weight of thetubes plus an increasing number of fins. With a machine according to thepresent invention, however, the tubes and the previously-fitted fins arestationary, and can more readily be supported; the movable carrier meansneed only support and move a cartridge of known and consistent weight.Clearly also, the likelihood of damage to the previously-fitted fins ismuch reduced if they remain stationary during the remainder of thefinning procedure, or alternatively stated less precautions need to betaken to prevent damage to the stationary fins.

The disadvantage of the prior art machine is more manifest if the numberof tubes in the assembled fin block is greater than two, since in suchcircumstances it is not feasible to assemble “sets” of fins as abovedescribed to two tubes and subsequently to another two tubes. The heatexchanger assembler would have to construct such a fin block as separatesmaller fin blocks, so avoiding the advantage of a single larger finblock.

Preferably, the periphery of the fins lies within the periphery of thesupport means, so that the support means can provide support tosubstantially the whole of the fin. However, in such embodiments it isnecessary that the support means be apertured to allow the tube(s) topass therethrough; it is desirable that the support means do not engagethe tube(s) whereas it is desirable that the fins do engage the tube(s).

Preferably, at least some of the support means are longitudinallymovable relative to the cartridge means. Such an arrangement allows thesupport means to adopt relatively widely-spaced positions during loadingof the fins into the cartridge, and closely-spaced positions duringfitment of the fins onto the tube(s). The closely-spaced positions maycorrespond to the desired spacing between the fins upon the tube.

Desirably, the support means are biassed apart by resilient biassingmeans. Such an arrangement results in the support means automaticallyadopting their widely-spaced positions prior to loading of the fins intothe cartridge. The support means can be forced into their closely-spacedpositions (perhaps by the carrier means) during the finning process.

In embodiments in which the support means have apertures through whichthe tube(s) can pass, the support means are preferably formed inseparable parts so that they can be separated from the fins followingfitment of the fins onto the tubes. In any event, the cartridge (and thesupport means carried thereby) must be able to move laterally relativeto the longitudinal axis of the tubes after fitment of the fins, sincethe presence of the fins will prevent longitudinal retraction of thecartridge. Preferably, the cartridge is separable from the finnedtube(s) whilst the tube(s) remains clamped by the clamping means, e.g.so that the cartridge can be re-filled with fins for subsequent locationonto the tube(s). Alternatively, the tube(s) must be removed from theclamping means before the cartridge can be separated from the finnedtube, it being arranged that successive cartridges can be used if alarge number of fins is to be fitted to the tube(s).

Desirably, in embodiments having movable support means, the supportmeans carry spacing means. The purpose of the spacing means is to definethe minimum separation between adjacent support means, and may bedesired in applications utilising fins with collars. Thus, the spacingmeans can if desired ensure that the support means (and therefore thefitted fins) are spaced apart by a distance greater than the length ofthe collars, so that the support means can be removed from between thefitted fins without fouling the collars. Alternative arrangements arepossible in which the collars project into the plane of the supportmeans during fin fitment, but in those embodiments it is desired thatthe spacing means and support means together ensure that the collar ofone fin does not become interlocked with the collar of an adjacent fin.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example, with referenceto the accompanying schematic drawings, in which:

FIG. 1 shows a tube finning machine according to the invention, prior tofitment of several common-fins to two tubes;

FIG. 2 shows a plan view, partly in section, of a cartridge meanssimilar to that of the machine of FIG. 1;

FIG. 3 shows a view similar to FIG. 2 of an alternative cartridge meansprior to loading of the fins;

FIG. 4 shows the cartridge of FIG. 3 during tube finning;

FIG. 5 shows a sectional view along the line V—V of FIG. 4;

FIG. 6 shows a sectional view along the line VI—VI of FIG. 4;

FIG. 7 shows a view of a wall member of another alternative cartridgemeans;

FIG. 8 shows a carousel arrangement for the clamping means; and

FIG. 9 shows a side view of part of yet another alternative cartridgemeans.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In this description, directional terms such as “top”, “bottom”, “upper”,“lower” etc. refer to the orientation of the machine and its componentsas drawn in FIG. 1, which is foreseen to be the normal orientation ofuse. However, the use of a machine at other orientations (e.g. with thetubes standing, or suspended, substantially vertically) is not excluded,and the relative directional terms can be translated to suchorientation.

In this embodiment the machine 10 comprises a substantially rigid base12, at one end of which is a fixedly mounted clamping means 14. The basehas a pair of guide bars 16, upon which can slide carrier means 18. Thedrive means for moving the carrier means 18 in this embodiment is alinear motor of known design which includes a first winding 20 mountedupon the base 12 and arranged substantially parallel to the longitudinalaxis A—A of the base 12, and a second winding (not seen) located withinthe carrier means 18; the second winding slides with the carrier means18 closely adjacent the first winding 20. The electrical wires leadingto the first and second windings are of known form, and are not shown.

In alternative embodiments other drive means could be employed, such ashydraulic, pneumatic, or screw drive, as might be desired in theparticular application.

In this embodiment, the clamping means 14 is adapted to secure the endsof two tubes 22 so that the tubes are held substantially rigidlyrelative to the base 12. The clamping of the ends of the tubes can be byany suitable means (several of which are described in WO96/35093 forexample).

Located upon the carrier means is a cartridge means 24, into which havebeen loaded several extended surface members or fins 26. In thisembodiment there are nine fins 26, adjacent fins being separated byrespective support means or wall members 30 (see also the wall members130 of FIG. 2). The end walls of the cartridge means 24 have openings 32therethrough, and the wall members 30 have similar openings, so that thetubes 22 can pass therethrough, preferably without contacting theperiphery of the openings.

As better seen in FIG. 2, the fins 26,126 in the embodiments describedherein are common-fins, i.e. each fin 26,126 has two apertures 34, sothat each can be connected to both of the tubes 22. It is expected thatthe present invention will almost invariably utilise common-fins, thoughit could clearly be used to apply separate, individual, fins to one ormore tubes at the same time, depending upon the application for whichthe finned tube is intended.

The walls 30,130 are an integral part of the cartridge means 24,124, andin the embodiments of FIGS. 1 and 2 are immovable relative to theremainder of the cartridge means. The separation S between the adjacentwall members determines the separation between the fins in the assembledfin block. Thus, it will be understood that when the cartridge means ismoved towards and around the tubes 22, the tubes 22 engage the collars36 of the fins 126. It is desired that the collars 36 face in thedirection of relative movement of the tubes, i.e. in the embodiment ofFIG. 2 the collars are directed towards the right and the tubes willmove relatively towards the right as the fins are inserted thereonto.Since the collars 36 are designed to be a frictional fit around thetubes 22, the tubes will act to push each fin towards the right until itengages its adjacent wall member 130. It will be noted that duringfitment of the fins 126 they are substantially fully supported by therespective wall members 130, so that they are not likely to deform evenif they are relatively thin, and/or the friction between the tube andcollar is considerable.

It will be recognised that when the fins have been fitted onto thetubes, it is not possible to withdraw the cartridge means 24,124longitudinally relative to the tubes, i.e. in the direction along theaxis A—A. It is therefore necessary that the cartridge means 24,124 beremoved laterally, and for this purpose the cartridge means 24,124 issplit longitudinally substantially along its mid-line 38 (FIG. 1),permitting the top half to be removed upwardly and the bottom half to beremoved downwardly.

In the embodiment of FIGS. 3 and 4, the wall members 230 are movablymounted within the cartridge means 224, and are biassed apart byrespective compression springs 40. Mounted to the cartridge 224 areguide bars 42. The wall members 230 are slidably mounted upon the guidebars 42, and the compression springs 40 are located upon guide bars 42.

The wall members 230 each carry spacers 44, which serve to determine theminimum separation between the wall members 230, and thus to determinethe separation s between the fitted fins (FIG. 4).

FIG. 3 shows the cartridge means 224 prior to loading of the fins. FIG.4 shows the cartridge means 234 following loading of the fins 226 andduring fitment onto the tubes 22. It will be noted that the cartridgeincludes an opening 46 which can accommodate an abutment 50 of thecarrier means, i.e. following loading of the fins 226 the abutment 50can be moved from a position shown in dotted outline to a position shownin solid outline, during which movement the springs 40 are compressedand the separation between adjacent fins 226 is reduced to the desiredfin spacing s.

The point at which the compression of the springs 40 occurs will dependupon the rating of those springs and the resistance to movement of thefins 226 along the tubes 22. Thus, the drive means acts through theabutment 50 directly upon (and in this embodiment only upon) the wallmember 230 a, and that wall member 230 a will drive the whole of thecartridge 224 until the frictional resistance to such movement (perhapscaused by the leading fin or fins 226 engaging the tubes 22) exceeds therating of the springs 40, whereupon the springs 40 will successively becompressed. It is of course necessary to arrange that the combinedspring rating is lower than the overall power of the machine, so thatall of the springs are fully compressed when the lead fin has beenpushed to its predetermined position upon the tubes, ensuring that allof the other fins are similarly positioned in their predeterminedpositions. The rating of the springs 40 will typically be small, sincethey are only required to force the wall members 230 apart to permitease of loading of the fins.

It will be noted that in the embodiment of FIGS. 3 and 4 the spacers 44project towards the left (as drawn) from their respective wall members.The effect of this is that the collars 36 of the fins are maintainedaway from the openings 52 of the wall members 230. However, it alsoresults in less than complete support for the fins during fitment ontothe tubes. It might be desired to increase the area of the spacers toincrease the support for the fins. In alternative embodiments, however,the spacers can project towards the right (as drawn) from the respectivewall members, so that during fitment the fins are substantially fullysupported by the respective wall members. In yet further alternativeembodiments, the spacers are omitted, and the fitted fins are separatedby a spacing corresponding to the thickness of the wall members 230.Such spacing could be close to the dimension of the collar, but it isdesirable in certain embodiments that the cartridge means separate thefins by a sufficient distance to prevent interlocking of adjacentcollars, which interlocking significantly increases the frictionalresistance to movement of the fins along the tubes.

As seen in FIGS. 5 and 6, the cartridge means 224 is mounted to slidealong the base, specifically along guides 52 which lie parallel to thelongitudinal axis A—A. The carrier means 18 is also mounted to slidealong the base, specifically along guides 54. Clearly, the form of theguides 52,54 can be chosen as desired, and the form of the guides forthe cartridge means 224 might be substantially identical to the form ofthe guides for the carrier means 18, for example. In the embodimentshown the cartridge means 224 may simply be placed into the guides 52,but in alternative embodiments the cartridge means might be moresecurely fastened to the base, e.g. it might be securable to guidemembers permanently (but slidably) mounted to the base.

The embodiment of FIGS. 3–6 has a split 238 along its mid-line, so thatthe top “half” of the cartridge means can be moved upwardly to separateit from the finned tube, whilst the bottom “half” can be moveddownwardly. The two “halves” can be secured together by any suitablereleasable fastening means. Since the split 238 also necessarily crossesthe wall members 230, four guide bars 42 are provided, one to eitherside of the wall members 230 above and below the split 238.

In the alternative embodiment of FIG. 7, the cartridge means 324 is notsplit but instead is designed to be removable as a single componentupwardly following fitment of the fins upon the tubes. Thus, the endwalls of the cartridge means (not shown) and the wall members 330, allincorporate open-sided apertures 60, the apertures allowing passage ofthe tubes 22 therethrough, but also subsequently allowing separation ofthe cartridge means from the finned tube. It will be noted that theremust be provision for preventing the fins from falling out of thecartridge following loading thereinto, and in this embodiment this isprovided for in that the cartridge lies directly upon the carrier means18, and the fins are loaded into the cartridge after the cartridge hasbeen placed upon the carrier means 18. In alternative embodiments inwhich it is desired that the cartridge be loaded away from the machine(so as to reduce the “down-time” of the machine) other suitable meansfor preventing the fins from falling out of the cartridge can beprovided, which .means can be removed once the cartridge is mounted uponthe machine and the fins are supported by the carrier means (or aresupported by the tubes during finning). In another embodiment, theledges 62 which are secured to the side walls 64 of the cartridge means324 can include movable projections which can support the fins as theseare loaded thereinto and during fitment onto the tubes 22, but which canbe moved to allow the cartridge means 324 to be separated from thefinned tubes.

In the embodiment of FIG. 7 the wall members 330 are movable, and thecartridge means has two guide bars 342 upon which the wall members aremounted in similar fashion to the embodiment of FIGS. 3–6. In analternative embodiment the wall members can be secured in fixedpositions relative to the side walls.

FIG. 8 shows a carousel clamping means 66 for the ends of the tubes. Inthis embodiment, the tube 68 is bent into a “U” shape, which is notuncommon in heat exchanger applications. The base of the “U” is clampedbetween the jaw 70 and the housing 72 (which clamping might be effectedby hydraulic or pneumatic pressure, for example, or by a nut and bolt,as desired). Only one U-shaped tube 68 is shown, though in practice upto six tubes 68 could be secured to the carousel, so that in use oneU-shaped tube could be facing the carrier means in the finning position,whilst other tubes could be in position to be removed from the carouselfollowing finning, and further tubes could be in position, or preparedto be located in position, ready for finning.

The carousel arrangement can increase the utility of the machine byreducing the down-time associated with clamping the tube(s) intoposition prior to finning, and subsequently removing the finned tubes.

In the embodiment of FIG. 9, the wall members 430 are placed at fixedlongitudinal positions in the cartridge means (i.e. they are not able tomove together and apart as in the embodiments of FIGS. 3–7. The wallmembers are each split at their mid-line 438, so that the top part ofthe wall member can be moved upwards to separate it from a fitted fin,whilst the bottom part can be moved downwards to separate it from thefitted fin. In this embodiment, however, the parts of each wall member430 can be moved independently of the other wall members and theremainder of the cartridge, and in FIG. 9 the parts of the leading wallmember 430 a have been moved to separate them from the leading fin 426a.

Following the separation of the wall member 430 a, the cartridge can bemoved farther to the left as drawn, the wall member 430 b driving thenext fin 426 b to the left, and into engagement with the collar 436 ofthe fin 426 a (if desired the engagement can be such as to interlock thetwo fins 426 a,b together so obtaining the benefits of suchinterlocking).

When the fin 426 b has been moved into engagement with the fin 426 a,the wall member 430 b can be separated, exposing the next fin which canbe subsequently moved into engagement with the collar of fin 426 b, andso on.

It can be arranged that the cartridge means of this embodiment does nothave a leading end wall to the left of the leading fin 426 a, so thatthe leading fin can be moved into engagement with the collar of anexisting fin, i.e. a fin which has previously been positioned upon thetube 422, perhaps by the movement of a previous cartridge means.

In FIG. 9, the fin 426 b is shown at a slight distance away from thewall member 430 b, but this is for reasons of clarity only. Thus, inpractice the wall member 430 b will drive the fin 426 b towards the leftas the cartridge is itself driven to the left by the carrier means, andso each fin member will engage its respective wall member.

It will be appreciated that the fin members 426 could be spaced apartwithin the cartridge means of FIG. 9 by any desired distance, and thewall members 430 could be as thick as required to ensure that neitherthey nor the fins will become deformed during fitment onto the tube(s).

The separation of the parts of the wall members can be effected by anysuitable means, such as for example pneumatic actuators. The parts ofthe wall members 430 can be arranged to slide within linear guideslocated in the side walls of the cartridge means. Following theseparation of all of the wall members (so that all of the fins whichwere loaded into the cartridge means have been fitted in theirpredetermined positions upon the tube(s)), the cartridge means can bewithdrawn longitudinally relative to the tube(s) 422, the parts of thewall members 430 being brought together once again when the cartridgemeans has cleared the end of the tube(s).

In the embodiments described the tube(s) are (substantially) fixedrelative to the base of the machine and the fins are movable relativethereto; this arrangement has considerable advantages as outlined above.Nevertheless, arrangements in which the fins are substantially fixedrelative to the base and the tubes are movable relative to the base, andin which both the fins and the tubes are movable relative to the base,and not necessarily excluded from the scope of the invention.

1. A tube finning machine for mounting extended surface members upon oneor more tubes, the machine having a base, a carrier movable relative tothe base, a driver for moving the carrier in a longitudinal direction,and a cartridge for locating a plurality of extended surface members,wherein the cartridge has respective support members for each extendedsurface member, and wherein at least some of the support members aremovable relative to the cartridge in the longitudinal direction.
 2. Atube finning machine for mounting extended surface members upon one ormore tubes, the machine having a base, a carrier movable relative to thebase, a driver for moving the carrier in a longitudinal direction, and acartridge for locating a plurality of extended surface members, whereinthe cartridge has respective support members for the extended surfacemembers, and wherein the support members are individually movablelaterally relative to the longitudinal direction.
 3. A tube finningmachine according to claim 1 in which each support member spans asubstantial part of the extended surface member.
 4. A tube finningmachine according to claim 3 in which the periphery of the extendedsurface members lie within the periphery of the support members.
 5. Atube finning machine according to claim 1 in which the support membersare resiliently biassed apart.
 6. A tube finning machine according toclaim 1 in which each support member comprises separable parts.
 7. Arube finning machine for mounting extended surface members upon one ormore tubes, the machine having a base, a carrier movable relative to thebase, a driver for moving the carrier, and a cartridge for locating aplurality of extended surface members, wherein a clamp is mounted to thebase for clamping a portion of at least one tube in a substantiallyfixed position relative to the base, and wherein the cartridge isconnected to the carrier so that said plurality of extended surfacemembers can be moved to an axially predetermined position relative tothe tube(s).
 8. A tube finning machine according to claim 7 in which thecartridge has a respective support members for each extended surfacemember.
 9. A tube finning machine according to claim 8 in which eachsupport member spans a substantial part of the extended surface member.10. A tube finning machine according to claim 9 in which the peripheryof the extended surface members lie within the periphery of the supportmembers.
 11. A tube finning machine according to claim 7 in which atleast some of the support members are movable relative to the cartridge.12. A tube finning machine according to claim 11 in which the supportmembers are resiliently biassed apart.
 13. A tube finning machineaccording to claim 8 in which each support member comprises separableparts.
 14. A tube finning machine for mounting extended surface membersupon one or more tubes, the machine having a base, a carrier movablerelative to the base, a driver for moving the carrier, and a cartridgefor locating a plurality of extended surface members, wherein thecartridge has a respective support member for each extended surfacemember, wherein each support member spans a substantial part of theextended surface member, wherein at least some of the support membersare movable relative to the cartridge tube finning machine and whereinthe support members are resiliently biassed apart.
 15. A tube finningmachine according to claim 14 in which each support member comprisesseparable parts.
 16. A method of mounting extended surface members toone or more tubes using a tube finning machine for mounting extendedsurface members upon one or more tubes, the machine having a base, acarrier movable relative to the base, a driver for moving the carrier ina longitudinal direction, and a cartridge for locating a plurality ofextended surface members, wherein the cartridge has respective supportmembers for the extended surface members, and wherein the supportmembers are individually movable laterally relative to the longitudinaldirection, the method comprising the following steps: {i} mounting oneor more tubes onto the machine, {ii} mounting the cartridge loaded witha plurality of extended surface members onto the machine, {iii}actuating the driver to cause the carrier to effect relative movement ofthe cartridge and tube(s) until the leading extended surface memberwithin the cartridge reaches a first predetermined position relative tothe tube(s), {iv} moving the support member of the leading extendedsurface member laterally relative to the cartridge, and {v} actuatingthe driver again to cause the carrier to effect further relativemovement of the cartridge and tube(s) until the next extended surfacemember within the cartridge reaches a second predetermined positionrelative to the tube(s).